This study assessed reliability of auditory sensory gating in young infants from 1-4 months of age using a paired-click paradigm in which auditory 'clicks' were presented at an interstimulus interval of 500 ms. Evoked potential component P1 was measured during periods of active sleep on two different occasions. Amplitudes, latencies, and ratio of the evoked potentials to each of the auditory clicks were compared. Significant reliability was found in the response ratio, response latency to the first stimulus, and response amplitude to the second stimulus, with a trend toward significance for response latency to the second stimulus and response amplitude to the first stimulus. The results suggest that auditory sensory gating can be reliably measured during active sleep in young infants and might be a useful tool in the study of neurodevelopmental disorders.